Conventionally, a magnetic recording medium is manufactured by coating magnetic material to a support and then dried, wherein ferromagnetic particles, a hardening agent, a dispersion agent, an abrasive, a lubricant, a matting agent, an antistatic additive, and other additives are added into a binder of the magnetic coating material and an adequate solvent is also added if necessary.
In order to improve the chemical stability of magnetic material, the following conventional method is widely known: a small amount of nickel, cobalt, titanium, silicon, and aluminum is added into the magnetic material in the form of a metal, a salt or an oxide; or the surface of the magnetic material is treated by the elements described above.
Conventionally, identical magnetic materials have been used for both the upper and lower layers of a multilayer magnetic recording medium in which magnetic materials treated by silicon, aluminum, and the like are used. For that reason, the content of silicon, aluminum and the like of magnetic materials in the upper and lower layers are equal.
However, this type of magnetic recording medium has the following disadvantages: after drying in the manufacturing process, the conveyance rollers (the conveyance rollers will be called the rollers hereafter in this specification) to convey the magnetic recording medium are stained by the magnetic recording medium; and the running efficiency of the magnetic recording medium is lowered when the temperature and humidity are high.
The objects of the present invention are to provide a magnetic recording medium characterized in that: the magnetic recording medium does not stain the conveyance rollers to convey the magnetic recording medium after the drying process during manufacture; and the running efficiency of the magnetic recording medium is high even when the temperature and humidity are high.
Another object of the present invention is to provide a magnetic recording medium characterized in that: the electromagnetic conversion characteristics are excellent; both sliding noise and dropout (D/O) are low; and the magnetic recording medium is suited for video tape use.